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Obsidian talus at Obsidian Dome, California Polished snowflake obsidian, formed through the inclusion of cristobalite crystals The Natural History by the Roman writer Pliny the Elder includes a few sentences about a volcanic glass called obsidian ( lapis obsidianus ), discovered in Ethiopia by Obsidius, a Roman explorer.
They can have an average diameter 5–20 centimetres (2.0–7.9 in), [3] but can be much larger (for example, 300–370 centimetres (10–12 ft) at Silver Cliff in Colorado). Lithophysae are also related to the spherulites found in obsidians on the Italian island of Lipari , in Yellowstone National Park , and other places.
1 Properties. Toggle Properties subsection ... This is an example of Ostwald's step ... Cristobalite is visible as the white inclusions in snowflake obsidian, a ...
Apache tears are rounded pebbles of obsidian or "obsidianites" composed of black or dark-colored natural volcanic glass, usually of rhyolitic composition and bearing conchoidal fracture. Also known by the lithologic term marekanite , this variety of obsidian occurs as subrounded to subangular bodies up to about 2 in (51 mm) in diameter, often ...
For example, snow tires which enhance traction during harsh winter driving conditions are labelled with a snowflake on the mountain symbol. [32] A stylized snowflake has been part of the emblem of the 1968 Winter Olympics, 1972 Winter Olympics, 1984 Winter Olympics, 1988 Winter Olympics, 1998 Winter Olympics and 2002 Winter Olympics. [33] [34]
Obsidian debitage is found in many of these tombs in addition to evidence of its use in temple dedications, potlaching, or offerings. For example, flakes have been found in association with stelae offerings and related to specific gods at the Maya site of Tikal. Its ritualized use is not, however, restricted to high-status political and ...
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For example, diamond and graphite are two crystalline forms of carbon, while amorphous carbon is a noncrystalline form. Polymorphs, despite having the same atoms, may have very different properties. For example, diamond is the hardest substance known, while graphite is so soft that it is used as a lubricant.